1. Field of Invention
The present invention relates generally to mixing dual and multi component dental materials in dentistry procedures, and specifically to an improved dental mixing device.
2. Description of Related Art
There are many dental procedures that require the mixing of two or more dental materials (also known as compositions, compounds, and substances) before the mixed dental material can be used in that particular dental procedure. In the past, a common practice was to measure the separate dental materials, drop them into a mixing dish, mix the dental materials together using an applicator brush, and then use the applicator brush to apply the mixed dental materials to the desired teeth surfaces. However, mixing using the applicator brush led to a host of problems including being tedious, time consuming, causing contamination from the patient's saliva, and having dental material evaporate or harden. For example, when bleaching teeth using peroxide, the peroxide will decompose immediately after mixing.
In view of such problems, auto-mixing dental mixing devices such as a dispensing syringe (also known as a double barrel syringe) were developed to address these problems. In general, dispensing syringes include two separate, elongated barrels (also known as chambers) that are arranged in a side-by-side configuration. The barrels are sealed, and the base paste is stored in one barrel, while the catalyst paste is stored in the other barrel. The barrels are connected to a dispensing tip.
In practice, the user, which is typically a dentist, pushes on the plunger of the syringe to force the base and catalyst pastes from their respective barrels and into the dispensing tip. The dispensing tip typically contains a static mixer. As the base and catalyst pastes are extruded through the static mixer, they are combined and mixed together to form the final, mixed dental cement. Then, the dentist can dispense the cement onto the desired target, for example, a temporary crown, and mount the crown over a crown-prepped tooth in the mouth of the patient. Dispensing syringes are used in dentistry for storing, mixing, and dispensing a wide variety of dental materials such as whiting gels, impression materials, dental filling materials temporary dental restoration materials, cements, and adhesives.
One example of a dispensing syringe is illustrated in Drake, U.S. Pat. No. 4,538,920. Drake discloses a dispensing device having a having a pair of chambers for storing dental resins separately and a pair of plungers that are forced into the chambers to discharge the resins. The device further includes a static-mixing element housed with an exit conduit and a discharge nozzle. The static-mixing element is held in a fixed position in order to maintain a predetermined alignment of a first blade in the static-mixing element relative to the two streams of resinous material.
Another example of a dispensing syringe is illustrated in Spehar et al., U.S. Pat. No. 4,753,536. Spehar discloses a double barrel syringe having two compartments for storing two separate dental polymeric materials, a discharge assembly, and a nozzle assembly for dispensing the material. The nozzle assembly comprises a common nozzle, a static-mixing element with an arm extending from one end. The static mixer is arbitrarily inserted into the bore of the nozzle. The discharge of the polymeric material from the compartments causes the static mixer to turn until the arm engages an end stop. The end stop prevents further rotation of the arm as material is fed into the nozzle, thereby allowing the mixer to intermix the two materials from the storage compartments.
Dentists often prefer working with these types of auto-mixing devices, such as dispensing syringes, because the base and catalyst pastes are stored in commercially-available cartridges and can be dispensed from the cartridges in a pre-determined volume ratio to form an optimally mixed composition. Thus, the dentist can save time using such auto-mixing devices and avoid mixing ratio errors.
However, the prior art falls short of truly simplifying the auto-mixing process. Prior to the use of a dispensing syringe, the mixing tip must be connected to the dual barrel container. This is because mixing tips are typically designed for a single use, since after one use the dental material hardens into cement within the tip such that the mixing tip cannot be reused. When the dentist wants to connect a new mixing tip to a dual barrel container, the dentist must pay close attention to align the outlets of the dual barrel container with the inlets of the mixing tip, along with paying attention to any other connection means (e.g., seal, threads, etc.). This alignment takes time, effort, and can be frustrating. Since this connection is typically performed while working with a dental patient, when time is of the essence, it is important that this connection be made quickly. Also, it is critical that the dentist's attention not be distracted from the dental procedure on hand.
Conventional devices exist to help fasten the mixing tip to the barrel, but do not simplify the attachment process. For example, U.S. Pat. No. 5,918,772 issued to Keller et al. discloses a bayonet fastening device for the attachment of an accessory to a multiple component cartridge or dispensing device. The bayonet attachment on the cartridge for attaching a mixer or accessory to a multiple component cartridge is formed as a ring-shaped bayonet socket with two internal recesses and two diametrically opposed cutouts forming one bayonet coupling part means, whereas the bayonet attachment of the mixer or accessory comprises two bayonet lugs corresponding to the cutouts. In a preferred embodiment the lugs and cutouts are of different widths for the coded alignment of the mixer or accessory to the cartridge in one predetermined position only.
U.S. Pat. Pub. No. 2011/0198,370 to Ho et al. discloses a device for mixing and discharging plural materials. The device for mixing and discharging plural materials has a body, a housing and a sealing plug. The body has multiple barrels and multiple tubes communicating with the barrels. The housing is rotatably attached to the body in a thread manner and has a mixing chamber and a discharging segment. The sealing plug is mounted in the mixing chamber to seal the tubes and has a sealing disk and multiple sealing sleeves.
Keller and Ho fall short because they do not simplify the alignment between the barrel and the tip. Instead, they tighten a connection that is already established. Kelly and Ho still require the user to carefully align the mixer's base/tip with the cartridge's outlets during installation. Additionally, Kelly and Ho lack a combination of hard and soft materials of a mixer and syringe tip that ensure a perfect seal and prevent cross contamination.